1、Designation: F 1498 00e1An American National StandardStandard Specification forTaper Pipe Threads 60 for Thermoplastic Pipe and Fittings1This standard is issued under the fixed designation F 1498; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、 of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEFig. 1 was editorially updated in November 2004.1. Scope1.1 This specification establishes requir
3、ements fordimen-sions and gaging of taper pipe threads used on threaded plasticpipe and fittings.1.2 Threads meeting this specification shall only be used onthose plastic materials deemed suitable by the manufacturer.1.3 Specialty threads or threads not requiring a leak-tightjoint are not covered in
4、 this specification.NOTE 1The terms “wrench makeup” and “wrench tight” are standardterminology for tightness and do not imply using a pipe wrench or othertools which would damage plastic pipe and fittings. The terms “hand-tight” and “hand-tight engagement” refer only to thread gaging (not pipeand fi
5、tting connections) and is the definition of the L1gage length.1.4 Thread DesignationsThe type of pipe threads in-cluded in this specification are designated by specifying insequence the nominal pipe size, number of threads per inch,and the thread series symbols as follows in accordance withANSI/ASME
6、 B 1.20.1:38-18 NPT. For left-hand threads addLH to the designation, otherwise right-hand threads will beunderstood. For example:38-18 NPT-LH.1.4.1 Each of these letters in the symbol has a definitesignificance as follows:N = National (American Standard)P = PipeT = Taper1.5 The values stated in inch
7、-pound units are to be regardedas the standard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regu
8、latory limitations prior to use. For specificprecautionary statements, see 7.2.1 and 8.3.2. Referenced Documents2.1 ASTM Standards:2D 1600 Terminology for Abbreviated Terms Relating toPlasticsE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsF 412 Terminology Relating to Plas
9、tic Piping Systems2.2 ANSI/ASME Standards:B 1.20.1 Pipe Threads, General Purpose (inch)3B 1.7M Nomenclature, Definitions and Letter Symbols forScrew Threads3B 47.1 Gage Blanks33. Terminology3.1 Terminology is in accordance with Terminology F 412and abbreviations are in accordance with Terminology D
10、1600,unless otherwise indicated.3.2 Nomenclature, definitions, and letter symbols for screwthreads are in accordance with ANSI/ASME B 1.7M.4. American National Standard Taper Pipe Thread Form4.1 Thread FormThe form of thread profile specified inthis specification shall be known as the American Natio
11、nalStandard Taper Pipe Thread Form. The relations as specifiedherein, for form of thread and general notations are shown inFig. 1.4.2 Angle of ThreadThe angle between the sides of thethread is 60 when measured in an axial plane. The linebisecting this angle is perpendicular to the axis.4.3 Truncatio
12、n and Thread HeightThe height of the sharpV thread, H, is as follows:H 5 0.866025p 5 0.866025/n (1)1This specification is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee F17.10 on Fittings.Current edition approved April 1, 2000.
13、Published July 2000. Originallypublished as F 1498 94. Last previous edition F 1498 94.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summar
14、y page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.where:p = pitch of thread, andn = threads per inch.4
15、.3.1 The basic maximum height of the truncated thread, h(see Fig. 1) is based on factors entering into the manufacture ofcutting tools and the making of tight joints.h 5 0.800p 5 0.800/n (2)The crest and root of pipe threads are truncated a minimumof 0.033p. Maximum truncation for the crest and root
16、 of thesepipe threads is in Table 1. The crests and roots of the externaland internal threads may be truncated either parallel to theH = 0.866025p = height of 60 sharp V thread b = 1 47 min. = thread taper angle for 1/16 taperh = 0.800000p = height of thread on product fc= depth of truncation at cre
17、stp =1/n = pitch (measured parallel to axis) fr= depth of truncation at rootn = number of threads per inch Fc= width of flat at cresta = 30 = thread flank angle Fr= width of flat at rootNOTE 1For a symmetrical straight screw thread, H = cot a/2n. For a symmetrical taper screw thread, H = (cot a tan2
18、b tan a)/2n, so that the exactvalue for an American National Standard Taper Pipe Thread is H = 0.865743p as against H = 0.866025p, the value given above. For an 8-pitch thread,which is the coarsest standard taper pipe thread pitch, the corresponding values of H are 0.108218 and 0.108253 respectively
19、, the difference being0.000035 in. This difference being too small to be significant, the value of H = 0.866025p continues in use for threads of 0.750 in., or less, taper/ft onthe diameter.FIG. 1 Basic Form of American National Standard Taper Pipe ThreadF 1498 00e12pitch line or parallel to the axis
20、.The sketches inTables 2-6 givea sectional view of this standard thread form, which representsthe truncated thread form by a straight line. However, whenclosely examined, the crests and roots of molded pipe threadsappear slightly rounded.4.4 Thread StartsMachinedFeathered starts are pro-duced by a 4
21、5 chamfer on the first thread when the thread iscut with a tap or die. The depth of chamfer shall be from34 to114 thread deep (see Fig. 2(a). Feathered starts are prone tocrossing and mutilation and shall not be molded.4.5 Thread StartsMoldedInternal and external moldedthreads shall begin with a tap
22、er or blunt start. A pilot shall beprovided from the face of the fitting and at the entering end ofthe external threads; it shall have a length to the start (flank) ofthe first thread, equal to12 to34 the width of the thread pitch,1to114 thread pitch to the centerline. (Thread pitch equals oneturn;
23、see Fig. 2(b) and Fig. 2(c).) The pilot shall be included inthe measurement of the thread length.4.5.1 Taper starts on the first thread are formed by the threadrising from the minimum to maximum diameter while main-taining the 60 thread profile (see Fig. 2(b). The length of riseshall not exceed18 tu
24、rn (45).4.5.2 Blunt starts on the first thread are formed by the threadrising from the minimum to maximum diameter while main-taining the 60 thread profile (see Fig. 2(c). The length of riseshall not be greater than twice the thread height. The blunt startis the preferred thread start.4.6 Plastic Th
25、readsGeneralThe minimum wall thick-ness (see Table 2) for the threaded portion of a plastic pipe orfitting depends upon the material and the application. If theTABLE 1 Limits on Crest and Root Truncation of American National Standard External and Internal Taper Pipe Threads, NPTAThreads/in.(n)Height
26、 ofSharp VThread (H)Height of Thread(h)Truncation (f) Equivalent Width of Flat (F)Min Max Tolerance Min Max ToleranceMax Min Formula Inch Formula Inch Formula Inch Formula Inch12345678910112131427 0.03208 0.02963 0.02496 0.033p 0.0012 0.096p 0.0036 0.0024 0.038p 0.0014 0.111p 0.0041 0.002718 0.04811
27、 0.04444 0.03833 0.033p 0.0018 0.088p 0.0049 0.0031 0.038p 0.0021 0.102p 0.0057 0.003614 0.06186 0.05714 0.05071 0.033p 0.0024 0.078p 0.0056 0.0032 0.038p 0.0027 0.090p 0.0064 0.003711.5 0.07531 0.06957 0.06261 0.033p 0.0029 0.073p 0.0063 0.0034 0.038p 0.0033 0.084p 0.0073 0.00408 0.10825 0.10000 0.
28、09275 0.033p 0.0041 0.062p 0.0078 0.0037 0.038p 0.0048 0.072p 0.0090 0.0042AThe basic dimensions of the American National Standard Taper Pipe Thread are given in inches to four and five decimal places. While this implies a greater degreeof precision than is ordinarily attained, these dimensions are
29、so expressed for the purpose of eliminating errors in computations.TABLE 2 ABS, CPVC, and PVC Reference InformationNominal PipeSize, in.Minimum Wall-Thickness, in. Minimum Hub-Diameter, in.Schedule 80PipeDWV Schedule 40and DWVSchedule 8018 0.095 . . . 0.526 0.64514 0.119 . . . 0.672 0.84038 0.126 .
30、. . 0.821 1.00012 0.147 . . . 0.998 1.28034 0.154 . . . 1.221 1.4501 0.179 . . . 1.504 1.810114 0.191 0.100 1.871 2.200112 0.200 0.088 2.127 2.4502 0.218 0.066 2.634 3.000212 0.276 . . . 3.170 3.5603 0.300 0.086 3.841 4.250312 0.318 . . . 4.374 . . .4 0.337 0.104 4.907 5.3505 0.375 . . . 6.039 . . .
31、6 0.432 . . . 7.203 7.6258 0.500 . . . 9.320 . . .10 0.593 . . . 11.614 . . .12 0.687 . . . 13.786 . . .F 1498 00e13wall thickness is not specified in a pipe or fitting standard, themanufacturer must determine the appropriate wall thickness.4.7 SealingWhere pressure-tight or leak-tight non-pressure
32、joints are required, it is intended that taper pipethreads conforming to this specification be made up with asealant-lubricant. Conventional pipe-thread compounds, putty,linseed oil-base products, and unknown mixtures shall not beused.NOTE 2Some TFE-fluorocarbon-paste compounds, even though theyare
33、recommended by the manufacturer, may not be compatible with someplastics.4.8 Thread TightnessWrench MakeupSome lubricants(PTFE pastes, silicones, etc.) may result in more finger-tightthread engagement than with sealants. The maximum recom-mended tightness is two turns past finger tight. Over tighten
34、ingwill produce hoop stresses greater than plastic can withstand,resulting in split fittings.NOTE 3When assembling metal and plastic threads, the preferredmethod is plastic male threads to metal female threads. Cyclic heating andcooling may result in dripping leaks.4.9 InspectionA gaging method of t
35、olerances is pre-scribed in this specification to effect a functional inspection ofthe hand-tight L1engagement threads. However, conformanceto this specification requires that all basic design dimensions bemet (within applicable tolerances) including extension of thethread elements (L2 L1) to provid
36、e for wrench-tight makeup.Therefore, additional methods of gaging may be employed toevaluate conformance to the basic design dimensions. WhenTABLE 3 Basic Dimensions of American National Standard Taper Thread, NPTANOTE 1Wrench makeup modified for plastic.NominalPipe Size,in.OutsideDiameter ofPipe (D
37、)Threads/in.(n)Pitch of Thread(P)Pitch Diameter atBeginning of Ex-ternal Thread (E0)Hand-tight Gage Engagement Effective Thread, ExternalLengthB(L1)DiameterC(E1)LengthD(L2)Diameter(E2)Inch Threads Inch Threads123 4 5 6789101116 0.3125 27 0.03704 0.27118 0.160 4.32 0.28118 0.2611 7.05 0.2875018 0.405
38、 27 0.03704 0.36351 0.1615 4.36 0.37360 0.2639 7.12 0.3800014 0.540 18 0.05556 0.47739 0.2278 4.10 0.49163 0.4018 7.23 0.5025038 0.675 18 0.05556 0.61201 0.240 4.32 0.62701 0.4078 7.34 0.6375012 0.840 14 0.07143 0.75843 0.320 4.48 0.77843 0.5337 7.47 0.7917934 1.050 14 0.07143 0.96768 0.339 4.75 0.9
39、8887 0.5457 7.64 1.001791 1.315 11.5 0.08696 1.21363 0.400 4.60 1.23863 0.6828 7.85 1.25630114 1.660 11.5 0.08696 1.55713 0.420 4.83 1.58338 0.7068 8.13 1.60130112 1.900 11.5 0.08696 1.79609 0.420 4.83 1.82234 0.7235 8.32 1.841302 2.375 11.5 0.08696 2.26902 0.436 5.01 2.29627 0.7565 8.70 2.31630212
40、2.875 8 0.12500 2.71953 0.682 5.46 2.76216 1.1375 9.10 2.790623 3.500 8 0.12500 3.34062 0.766 6.13 3.38850 1.2000 9.60 3.41562312 4.000 8 0.12500 3.83750 0.821 6.57 3.88881 1.2500 10.00 3.915624 4.500 8 0.12500 4.33438 0.844 6.75 4.38712 1.3000 10.40 4.415625 5.563 8 0.12500 5.39073 0.937 7.50 5.449
41、29 1.4063 11.25 5.478626 6.625 8 0.12500 6.44609 0.958 7.66 6.50597 1.5125 12.10 6.540628 8.625 8 0.12500 8.43359 1.063 8.50 8.50003 1.7125 13.70 8.5406210 10.750 8 0.12500 10.54531 1.210 9.68 10.62094 1.9250 15.40 10.6656212 12.750 8 0.12500 12.53281 1.360 10.88 12.61781 2.1250 17.00 12.66562AThe b
42、asic dimensions of the American National Standard Taper Pipe Thread are given in inches to four or five decimal places. While this implies a greater degree ofprecision than is ordinarily attained, these dimensions are the basis of gage dimensions and are so expressed for the purpose of eliminating e
43、rrors in computations.BAlso length of thin ring gage and length from gaging notch to small end of plug gage.CAlso pitch diameter at gaging notch (hand-tight plane).DAlso length of plug gage.F 1498 00e14additional methods of gaging are employed, they shall beagreed upon between the supplier and the p
44、urchaser. Because itis known that injection molded threads that are removed fromthe mold before they are completely cooled will distort in formso that they will not gage properly, threads suspected of beingso distorted should be inspected with an optical comparator todetermine their true quality.5.
45、Specification for General Purpose Taper Pipe Threads,NPT5.1 Taper Pipe ThreadsThreads made in accordance withthese specifications consist of an external taper and an internaltaper thread, to form a normal type of joint having generalapplication on pipe and fittings (see Fig. 3). The NPT taperpipe th
46、reads are intended to be made up wrench-tight (maxi-mum two turns past finger-tight), and with a lubricant orsealant whenever a pressure-tight or leak-tight nonpressurejoint is required (see 4.7 and 4.8). Sealing is affected byout-of-roundness which is possible between the wrench-tightmated parts in
47、 final assembly. This will vary depending on themethod for producing the thread in conjunction with theelasticity or ductility, or both, of the mating parts and theresultant conformance at final assembly.5.1.1 Thread Designation and NotationAmerican Na-tional Standard Taper Pipe Threads are designat
48、ed in accor-dance with 3.2 as follows:38-18 NPT.5.1.1.1 Standard notation applicable to American NationalStandard Taper Pipe Threads is shown in Fig. 4.5.1.2 Form of Thread:5.1.2.1 The basic dimensions of American National Stan-dard Pipe Threads, NPT, are given in Table 3 (wrench makeuphas been chan
49、ged from three turns to two turns for sizes 2 in.and smaller), which is for machined threads. (See 4.1.)5.1.2.2 The basic dimensions of molded taper pipe threadsfor pressure fittings are given in Table 4. The overall length(L4) is slightly less than that of American National StandardTaper Pipe Threads, NPT, because there are no vanish threads.5.1.2.3 The basic dimensions of molded taper pipe threadsfor DWV fittings are given in Table 5. The overall length (L4)is shorter than that of American National Standard Tape
